VITRINELLA. Panama Shells. 189 



Mean divergence about 170 ; greatest breadth .062 inch'; 

 least breadth .053 inch ; height .32 inch. 



Station. Unknown. 



Habitat. Panama; 0. B. A.! 



1 specimen was found in the calcareous sand. 



268. Titrinella tricarinata. Nov. sp. 



Shell subdiscoidal : white : with three prominent spiral keels, 

 one on the periphery of the last whorl, and one on each side of 

 it, of which the upper one is visible on the spire : with some 

 irregular transverse stride : spirally striate within the umbilicus : 

 apex subacute : spire convex, a little elevated : whorls three, 

 depressed above and compressed below the keel, with a distinct 

 suture : aperture oblique, orbicular, angulated by the keels : 

 umbilicus wide and deep. 



Mean divergence about 150 ; greatest breadth .072 inch ; 

 least breadth .065 inch; height .035 inch. 



Station. Unknown. 



Habitat. Panama ; C. B. A. ! 



1 specimen was found in the calcareous sand. 



269. Titrinella valvatoides. Nov. sp. 



Shell discoidal : whitish, sub-transparent : last whorl with a 

 prominent keel above, which is visible on the spire, with 

 another prominent keel beneath, and a third, less developed, 

 around the umbilicus: spire concave: whorls three, concave 

 above the keel, with a distinct suture : last whorl subangular at 

 the periphery : umbilicus wide and deep. 



Greatest breadth .1 inch ; least breadth .075 inch ; height .04 

 inch. 



Station. Unknown. 



